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a(2n) = n+2, a(2n-1) = smallest number requiring n+2 letters in English.
5

%I #10 Mar 30 2012 18:39:33

%S 1,3,4,4,3,5,11,6,15,7,13,8,17,9,24,10,23,11,73,12,3000,13,11000,14,

%T 15000,15,101,16,104,17,103,18,111,19,115,20,113,21,117,22,124,23,123,

%U 24,173,25,323,26,373,27,1104,28,1103,29,1111,30

%N a(2n) = n+2, a(2n-1) = smallest number requiring n+2 letters in English.

%C Requires presence of "and" at appropriate place, e.g. "one hundred and one" [Sean A. Irvine, Aug 29, 2011].

%Y Cf. A001166, A014388, A045494, A045495.

%K nonn,word,easy

%O 1,2

%A Jacques Haubrich (jhaubrich(AT)freeler.nl)

%E More terms from _Sean A. Irvine_, Aug 28 2011